<template>
    <div class="article-container">
        <van-nav-bar class="page-nav-bar" left-arrow @click-left="$router.back()" title="黑马头条"></van-nav-bar>
        <div class="main-wrap">

            <div v-if="loading" class="loading-wrap">
                <van-loading color="#3296fa" vertical>加载中</van-loading>
            </div>

            <!-- 文章详情 -->
            <div v-else-if="article.title" class="article-detail">
                <h1 class="article-title">{{article.title}}</h1>

                <!-- 用户信息 -->
                <van-cell class="user-info" center :border="false">
                    <van-image slot="icon" class="avatar" round fit="cover" :src="article.aut_photo"/>
                    <div slot="title" class="user-name">{{article.aut_name}}</div>
                    <div slot="label" class="publish-date">{{article.pubdate | relativeTime}}</div>

                    <!-- <FollowUser
                    class="follow-btn"
                    :userId="article.aut_id"
                    :isFollowed="article.is_followed"
                    @updateFollowed="article.is_followed = $event"/> -->
                    <!--$event获取传递过来的事件参数 -->

                    <FollowUser
                    class="follow-btn"
                    :userId="article.aut_id"
                    v-model="article.is_followed"/>
                    <!-- 组件中的v-model默认会通过props传递名为value的参数，并监听input事件修改其值
                        可在子组件中通过model属性来修改默认的参数名和事件名 -->
                </van-cell>

                <!-- 文章内容 -->
                <div class="article-content markdown-body"
                v-html="article.content"
                ref="article-content"></div>
                <van-divider>正文结束</van-divider>

                <!-- 评论列表 -->
                <CommentList :source="article.art_id"
                :list="commentList"
                @onLoadSuccess="totalCommentCount = $event.total_count"
                @replyClick="onReplyClick"/>

                <!-- 底部区域 -->
                <div class="article-bottom">
                    <van-button
                    class="comment-btn"
                    type="default"
                    round
                    size="small"
                    @click="isPostShow = true">
                        写评论
                    </van-button>
                    <van-icon class="comment-icon" name="comment-o" :badge="totalCommentCount" color="#777"/>
                    <CollectArticle class="btn-item" v-model="article.is_collected" :articleId="article.art_id"/>
                    <LikeArticle class="btn-item" v-model="article.attitude" :articleId="article.art_id"/>
                    <van-icon name="share" color="#777777"></van-icon>
                </div>

                <!-- 文章评论 -->
                <van-popup
                v-model="isPostShow"
                round
                position="bottom">
                    <CommentPost :target="article.art_id" @postSuccess="onPostSuccess"/>
                </van-popup>

                <!-- 评论回复 -->
                <van-popup
                v-model="isReplyShow"
                round
                position="bottom"
                style="height: 80%">
                <!-- 弹出层存在懒加载机制，第一次显示后其内容会被缓存，导致之后的回复都是相同内容
                    可使用v-if来销毁组件，已解决缓存问题 -->
                    <CommentReply v-if="isReplyShow" :comment="currentComment" @close="isReplyShow = false"/>
                </van-popup>
            </div>

            <!-- 加载失败：404 -->
            <div v-else-if="errStatus === 404" class="error-wrap">
                <van-icon name="failure" />
                <p class="text">该资源不存在或已删除！</p>
            </div>
            <!-- 加载失败：其它未知错误（例如网络原因或服务端异常） -->
            <div v-else class="error-wrap">
                <van-icon name="failure" />
                <p class="text">内容加载失败！</p>
                <van-button class="retry-btn" @click="loadArticle">点击重试</van-button>
            </div>
        </div>
    </div>
</template>

<script>
import { getArticleById } from '@/api/article'
import FollowUser from '@/components/follow-user'
import CollectArticle from '@/components/collect-article'
import LikeArticle from '@/components/like-article'
import CommentList from '@/views/article/components/comment-list.vue'
import CommentPost from '@/views/article/components/comment-post.vue'
import CommentReply from '@/views/article/components/comment-reply.vue'
import { ImagePreview } from 'vant'

export default {
    name: 'Article',
    props: ['articleID'],
    components: {
        FollowUser,
        CollectArticle,
        LikeArticle,
        CommentList,
        CommentPost,
        CommentReply
    },
    // 依赖注入：给所有后代组件传递数据
    provide: function () {
        return {
            articleId: this.articleID
        }
    },
    data () {
        return {
            article: {},
            loading: true,
            errStatus: 0,
            followLoading: false,
            commentList: [],
            totalCommentCount: 0,
            isPostShow: false,
            isReplyShow: false,
            currentComment: {}
        }
    },
    methods: {
        async loadArticle () {
            this.loading = true
            try {
                // 由于后端返回的id被json转为数字型，是个大整数，超出了js所能表示的范围(-2^53到2^53)因此无法精确表示
                // yarn add json-bigint
                const res = await getArticleById(this.articleID)
                console.log(res)
                this.article = res.data.data

                setTimeout(() => {
                    this.previewImage()
                }, 0)
            } catch (err) {
                if (err.response && err.response.status === 404) {
                    this.errStatus = 404
                }
                this.$toast('获取文章数据失败', err)
            }
            this.loading = false
        },
        previewImage () {
            const articleContent = this.$refs['article-content']
            const imgs = articleContent.querySelectorAll('img')
            const images = []
            imgs.forEach((img, index) => {
                images.push(img.src)
                img.onclick = () => {
                    ImagePreview({
                        // 图片地址数组
                        images,
                        // 起始位置，从0开始
                        startPosition: index
                    })
                }
            })
        },
        onPostSuccess (data) {
            this.isPostShow = false
            this.commentList.unshift(data.new_obj)
        },
        onReplyClick (comment) {
            this.currentComment = comment
            this.isReplyShow = true
        }
    },
    created () {
        this.loadArticle()
    }
}
</script>

<style scoped lang="less">
@import "./github-markdown.css";

.article-container {
    .main-wrap {
        position: fixed;
        left: 0;
        right: 0;
        top: 92px;
        bottom: 88px;
        overflow-y: scroll;
        background-color: #fff;
    }
    .article-detail {
        .article-title {
            font-size: 40px;
            padding: 50px 32px;
            margin: 0;
            color: #3a3a3a;
        }
        .user-info {
            padding: 0 32px;
            .avatar {
                width: 70px;
                height: 70px;
                margin-right: 17px;
            }
            .van-cell__label {
                margin-top: 0;
            }
            .user-name {
                font-size: 24px;
                color: #3a3a3a;
            }
            .publish-date {
                font-size: 23px;
                color: #b7b7b7;
            }
            .follow-btn {
                width: 170px;
                height: 58px;
            }
        }
        .article-content {
            padding: 55px 32px;
            /deep/ p {
                text-align: justify;
            }
        }
    }
    .loading-wrap {
        padding: 200px 32px;
        display: flex;
        align-items: center;
        justify-content: center;
        background-color: #fff;
    }
    .error-wrap {
        padding: 200px 32px;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        background-color: #fff;
        .van-icon {
            font-size: 122px;
            color: #b4b4b4;
        }
        .text {
            font-size: 30px;
            color: #666666;
            margin: 33px 0 46px;
        }
        .retry-btn {
            // width: 280px;
            height: 70px;
            line-height: 70px;
            border: 1px solid #c3c3c3;
            font-size: 30px;
            color: #666666;
        }
    }
    .article-bottom {
        position: fixed;
        left: 0;
        right: 0;
        bottom: 0;
        display: flex;
        justify-content: space-around;
        align-items: center;
        box-sizing: border-box;
        height: 88px;
        border-top: 1px solid #d8d8d8;
        background-color: #fff;
        .comment-btn {
            width: 282px;
            height: 46px;
            border: 2px solid #eeeeee;
            font-size: 30px;
            line-height: 46px;
            color: #a7a7a7;
        }
        /deep/ .van-icon {
            font-size: 40px;
        }
        .comment-icon {
            top: 2px;
            color: #777;
            .van-info {
                font-size: 16px;
                background-color: #e22829;
            }
        }
        .btn-item {
            border: none;
            padding: 0;
            height: 40px;
            line-height: 40px;
            color: #777777
        }
        .collect-btn--collected {
            color: #ffa500;
        }
        .like-btn--liked {
            color: #e5645f;
        }
    }
}
</style>
